Bubotuber

A bubotuber looks like a thick, black, giant slug (it even squirms slightly, although it sticks vertically out of the soil) with many large shiny swellings on it that are filled with a yellow-green pus that smells like petrol (GF13).

As Professor Sprout taught her fourth-year students, the pus reacts oddly with human skin. Undiluted, it will raise horribly painful boils on contact (GF28), but properly diluted and processed can be used to cure acne (GF13). The pimple-curing properties were discovered by Sacharissa Tugwood (FW). (Also JKR -W1).

During the Tri-Wizard Tournament, after journalist Rita Skeeter wrote that Harry and Hermione were in a love triangle with Viktor Krum, Hermione received an envelope full of undiluted bubotuber pus that made her hands swell up. (GF14)

bubo = (Gr. boubôn, "groin") (plural form: buboes) is a swelling of the lymph nodes. It is found in infections such as bubonic plague. It is similar in appearance to a huge blister, and usually appears under the armpit, in the groin or on the neck.Tuber = In anatomy, the term tubercle may describe a round lump or warty outgrowth found on bones or skin, or, in cases of tuberculosis, in the lungs (Wikipedia). A tuber is also the root that is characteristically enlarged in tuberous plants such a potatoes and yams.